The DA 12-24mm f/4 ED (IF) is Pentax’s only dedicated wide-angle lens for its APS-C DSLRs...
...although users of this system also have the choice of the Sigma and Tamron lens’ featured in our test. This lens has a full-frame equivalent focal length of 18-34mm when the 1.5x crop factor has been applied, and features a maximum constant aperture of f/4. Inside the lens there are 2 aspherical elements and 1 ED (Extra-low Dispersion) element to reduce distortion, and the 13 lens elements are arranged in 11 groups.
The 12-24mm has no internal AF motor and so the autofocus generates a moderate degree of noise, but still operates with satisfying speed. There’s a Quick Shift focusing system that allows for instant manual override. As the lens achieves focus internally the front element of the lens doesn’t rotate, so it’s possible to use polariser filters that match the 77mm filter thread.
The 12-24mm performed well. With the zoom set to 12mm detail is very sharp across the entire frame, at all aperture settings. When zoomed in to 24mm, the centre remains sharp but the corners become a little more fuzzy. The lens was at its sharpest at f/11. We did detect a fair amount of chromatic aberration and some barrel distortion in test images – more pronounced at the wide end of the zoom – and some vignetting with the aperture wide open.
Constant f/4 aperture
Pleasing image quality
More expensive than rivals
Focusing noisy as no AF motor
Min aperture: f/22
Filter size: 77mm